This short video will provide with a better understanding of the development of the amniotic cavity and yolk sac. It uses three dimensional imaging to explain the process of embryo folding and the consequent downard folding of amniotic cavity. 0:00 Introduction 0:22 Formation of Amniotic Cavity & Yolk Sac 1:25 Folding Downard of Amniotic Sac 2:01 Formation of Yolk Stalk & Primitive Gut 3:15 Future of Amniotic Cavity & Yolk Sac